In the field of furniture industry, in particular of valuable furniture, the need to provide furniture elements having a linear and minimalist appearance and a particular aesthetic lightness, which at the same time have a high structural solidity, is increasingly felt.
This need is particularly felt in the field of bookcases, which must be designed to stably withstand weights of high intensity, such as those of a large number of books arranged on the shelves of the bookcase.
As mentioned above, the aesthetic needs of a valuable bookcase require that such a high structural stability is obtained by means of a seemingly light and thin structure. These two requirements are clearly conflicting.
A technique is known of reinforcing the structure of a cabinet having uprights and shelves by means of back panels which fit between superimposed shelves and between the uprights of the structure, but as mentioned above, this solution clashes with the need to provide a structure with a clean and minimalist appearance. On the contrary, the quality design requires providing a self-supported structure without back panels. In addition, the presence of back panels would prevent arranging the bookcase in a central area of a room since the back panel of the bookcase would be a visual hindrance between the two sides of the room separated by the bookcase. On the contrary, when the bookcase is not leaning against a wall but positioned at the center of a room, it should be accessible from both opposite directions of approach to the same.
Another known technique for reinforcing a structure formed by uprights and shelves and without a back panel is to reinforce the structure with tie-rods having ends fixed to different elements of the structure, between the edges of the structure itself to prevent the relative rotation between uprights and shelves.
It is clear that this solution also contrasts with the needs dictated by the quality design.
Among the other things, the quality design cannot envisage the use of visible reinforcement brackets between uprights and shelves.
These needs of reinforcing the structure of a cabinet adapted to withstand high weights are amplified if the structure of the bookcase includes shelves mounted as cantilever shelf starting from an upright. In these circumstances in which the shelf is fitted only at one end thereof and has the opposite free end not supported, the stresses which weigh on the fixing area of the shelf to the upright are the most severe. This stress increases proportionally to the distance of the point of application of the load on the shelf with respect to the upright.
Therefore, it is a problem particularly felt to improve the solidity of the structure of a piece of furniture, or of a bookcase, in order to withstand high static stresses avoiding any reinforcement element visible from the outside. Even more deeply felt is the need to provide a reinforced bookcase having cantilever shelves of long arm, avoiding any reinforcement device visible from the outside.